Field of the Invention
The present invention relates generally to devices and arrangements of devices for heating surfaces and, in particular, to a portable heating arrangement including a heating conduit extending across a surface, such as a roof, and/or through a trough or channel, such as a rain gutter, for the purpose of preventing the buildup of ice and snow.
Description of Related Art
Accumulation of ice and snow on roofs and in rain gutters presents a variety of problems for property owners. For example, accumulated ice and snow apply pressure against a roof and gutter which, over time, weakens the structure. Furthermore, accumulated ice and snow may thaw and freeze many times over the course of the winter permitting water to collect in cracks and to expand during freezing, further weakening the roof and gutter structure. Additionally, accumulated ice and snow may block gutters. As a result, during rainstorms the gutter overflows causing water damage to the building or property. Further still, accumulated ice and snow can cause rust, damaging metal portions of a roof or gutter and causing the structure to degrade prematurely.
In view of these problems, various heating systems are available to melt ice and snow from roofs and gutters to prevent accumulation of ice and snow. For example, electric radiant heating systems consisting of a conductive wire or cable permanently installed on a roof or inserted along a rain gutter, are well known. When a user becomes concerned that snow and ice is accumulating, the user turns on the system causing the cables to heat up, thereby melting the snow and ice.
There are two main types of electric radiant heating cables, constant wattage cables and self-regulating cables. When electricity is applied, constant wattage cables maintain a fixed wattage output and, consequently, produce only one level of heat. With systems including self-regulating cables, the wattage of the cables (and, correspondingly, the heat output) increases as the temperature drops. Self-regulating cables tend to be more durable than constant wattage cables, but are also more expensive.
Typically, these permanent systems are installed by a roofer and/or an electrician (hereinafter “the installer”). The installation process tends to be a time consuming and rather labor intensive process. Initially, the installer selects, measures, and lays out a pattern for the heating cables along the roof surface and through the gutter. The cables are often arranged in a “zig-zag” pattern extending longitudinally along the roof surface near the lower edge of the roof and into the gutter.
Once the correct path for the wire is laid out, the installer installs roof clips directly to the roof in accordance with the selected pattern. For example, the roof clips may be fastened below the shingle with a nail or screw. Roofing cement or adhesive may also be used to secure the clips to the roof. Alternatively, the clip may be installed on top of the shingle by driving the fastener through the shingle. Once the clips are in place, the installer weaves the cable through the clips to attach the cables to the roof. The clips and cable are permanently installed on the roof and are intended to remain in place for the entire useful life of the heating system. When the cables fail, the old cables must be removed and the entire installation process repeated. Most constant wattage cables have one or two year warranties. Self regulating cables have warranties of about five to ten years.
Known systems using permanently installed heating cables have numerous drawbacks. Most significantly, such permanent systems are expensive as a result of both the cost of the cables themselves, which can be several hundred dollars, and the labor intensive installation process. In addition, the useful life of the heating system is limited by the lifespan of the cable. Even more durable self-regulating cables are only under warranty for five to ten years; in comparison, a newly installed roof may last 30 years or longer.
Furthermore, while wear and tear caused by snow and ice accounts for some of the degradation of the installed systems, the greatest impact on the lifespan of the cables is from prolonged exposure to solar ultraviolet (UV) radiation, which breaks down the rubber or synthetic polymer casing surrounding the cable. Continual heating and cooling of the cable also causes the wires to swell and contract over time, which weakens the clips and roof shingles. Thus, exposure to the elements during the summer months, when UV levels and temperature are higher, contributes to the breakdown of the heating cables as much as exposure to ice and snow during winter. Still further, the permanent cable systems trap debris such as dead leaves and vegetation in the gutter, meaning that gutters must be cleaned more frequently. Blockage of gutters is especially problematic during spring and autumn, when dead leaves and vegetation are most likely to accumulate on roof surfaces. Finally, property owners dislike the appearance of wire heating systems and would prefer if such systems were not visible during times of the year when they are most likely to be outside and able to see the installed cables.